Paraquat, an herbicide that causes delayed pulmonry edema, is structurally similar to decamethonium. It was found to have weak anticholinergic effects in chicks. The turnover of membrane phospholipids has been examined, since acetylcholine causes increased turnover of phospholipids. The effects of paraquat on incorporation of labeled phosphate into the phospholipids of rat lung slices showed a 50 percent increase into phosphatidic acid and slight decreases into phosphatidylcholine and phosphatidic acid. Propranolol, which has been shown to reduce the LD50 of paraquat in rats, doubled the incorporation into phosphatidylglycerol, increased fivefold the incorporation into phosphatidic acid and increased twelvefold the incorporation into a lipid presumed to be cytidine diphosphate-diglyceride.